Troubleshooting an overdrive pedal

[ollehu]

Hi,

I'm new to this forum and to building guitar pedals as well. My first project was to build an overdrive pedal, more specifically this clone of another famous pedal: https://www.amazon.com/gp/product/B01N0K3NUI/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

I have some experience with soldering from a couple of keyboard projects and did not find that part too difficult. But still, I must have made some mistake along the way. I can plug in the pedal and activate it properly (getting the diode to light up), but it's emitting mostly noise to the amplifier. The guitar can be heard through the noise, but it is evident that something else is wrong. So far I've tried some of the debugging guides provided here in the forum, but without any success.

I have attached two images of the PCB. Further, I've measured to voltages at all of the integrated circuits, and those are provided below:

IC1 (top left):
P1: 9V
P2: Square wave, 6.4V RMS, 20us cycle time
P3: 0V
P4: Same as P2 with opposite sign
P5: -8.7V
P6: 4.5V
P7: 3.8V
P8: 9V

IC2 (middle one):
P1: 4.6V
P2: 4.6V
P3: 4.5V
P4: -8.7V
P5: 4.5V
P6: 4.6V
P7: 4.5V
P8: 16.7V

IC2 (right one):
P1: 4.5V
P2: 4.5V
P3: 1.25V
P4: 0V
P5: 4.4V
P6: 4.5V
P7: 4.6V
P8: 9V




Does anyone have any similar experience with this pedal and could push me in the correct direction when it comes to troubleshooting? Many thanks, and please let me know if I'm missing any kind of information in this post.

[Kevin Mitchell]

Hello & welcome to the forum!

First off you should reflow all solder joints. There looks to be quite a few bad solders as well as some that don't appear to be soldered at all. See what happens from there and report back.

[deadastronaut]

i would reflow quite a few of those pads/joints. some barely have solder on them.

also, test your jacks to make sure you have the tip and sleeves correctly wired.

edit: kevin beat me to it..

[Mark Hammer]

It's a simple thing, and probably one that doesn't need attending to, but I'll ask it anyway just so it can be checked off the list.

Are any electrolytics seeing the boosted/pumped supply-voltage rated LESS than 25V? (one generally doesn't see ratings between 16 and 25Vdc).

[ollehu]

All right, thank you all for the advice. I will try to reflow the joints this weekend and see where that gets me!

[MrStab]

Hi,
Have you read the comment from Art Vandelay in the reviews in the Amazon link you posted? There's also another review listing issues down at the bottom (by user Al Hardiman).

What does the chip say on it? It at least LOOKS like an 7660S, but i can't see the text.